Wafer-scale heterostructured piezoelectric bio-organic thin films

Piezoelectric bioorganic thin films Piezoelectric materials enable a reversible conversion between mechanical pressure and electric charge and are useful for sensors, actuators, and high-precision motors. Yang et al. developed a method for making high-quality crystalline thin films of piezoelectric γ-glycine crystals that are grown and refined between layers of polyvinyl alcohol (PVA) (see the Perspective by Berger). The PVA layers are essential to promoting the crystallization of the preferred crystal phase with the polar axis oriented perpendicular to the film plan because of hydrogen bonding at the PVA-glycine interface. The thin films show a macroscopic piezoelectric response and high stability in aqueous environments. The films are water soluble and, when suitably packaged, could be implanted into a biodegradable energy-harvesting device. Science , abf2155, this issue p. 337 ; see also abj0424, p. 278